# TNF-Blockers: Infection and Cancer Risks

## Explore safety/mechanism links for TNF-blocker associated infections and malignancies

## Abstract

TNF-blockers demonstrate mechanistically coherent infection risks linked to TNF’s essential role in immune surveillance and host defense. While overall infection risk shows only modest increases (OR 1.18-1.20) that become non-significant when adjusted for exposure time (IRR 1.01), opportunistic infections show consistent 90% increased risk (OR 1.90) and tuberculosis risk increases 3- to 4-fold (OR 3.3-3.5). The mechanism centers on disruption of granuloma formation, explaining why tuberculosis occurs exclusively with monoclonal antibodies that completely neutralize TNF and why 72% of infliximab-associated granulomatous infections occur within 90 days, consistent with reactivation of latent infections rather than increased susceptibility to new pathogens. Agent-specific differences are substantial, with infliximab carrying 3.25-fold greater granulomatous infection risk than etanercept, reflecting mechanistic differences between complete TNF neutralization and partial receptor blockade.

For malignancies, competing biological mechanisms—TNF’s dual roles in suppressing tumors through apoptosis versus promoting cancer through chronic inflammation—generate heterogeneous findings that resolve upon careful examination. Long-term observational studies show no overall increased malignancy risk (OR 0.90-0.95) and no evidence that longer exposure increases risk, while short-term RCT meta-analyses finding elevated risk (OR 3.3) likely reflect detection bias given inadequate latency periods for cancer development. Skin cancers represent the most consistent signal (OR 1.45 for non-melanoma skin cancer), amplified by concomitant methotrexate (RR 1.97). For lymphomas, standardized incidence ratios of 1.8-6.0 in rheumatoid arthritis must be interpreted against 2-fold baseline elevation from systemic inflammation itself, and pooled estimates controlling for this confounding show no significant TNF-blocker effect (OR 1.11). The mechanistic framework suggests that baseline inflammatory disease severity, rather than immunosuppression per se, drives most malignancy risk in these populations.

## Methods

We analyzed 10 sources from an initial pool of 200, using 8 screening criteria. Each paper was reviewed for 7 key aspects that mattered most to the research question.

## Characteristics of Included Studies

| Study | Full text retrieved? | Study design | Patient population | Sample size (treatment/control) | TNF-blockers studied | Follow-up duration |
| --- | --- | --- | --- | --- | --- | --- |
| E. Dommasch et al., 2011 | Yes | Systematic review and meta-analysis of RCTs | Plaque psoriasis and psoriatic arthritis | 4,598/2,313 | Etanercept, infliximab, adalimumab, golimumab, certolizumab | Mean 17.8 weeks (range 12-30 weeks) |
| S. Minozzi et al., 2016 | Yes | Systematic review and meta-analysis of RCTs and open-label extension studies | Rheumatoid arthritis, psoriatic arthritis, ankylosing spondylitis | 14,766/7,994 | Adalimumab, golimumab, infliximab, certolizumab, etanercept | 1-36 months (RCTs), 6-48 months (open-label extensions) |
| M. Muller et al., 2020 | No | Systematic review of observational cohort studies | Inflammatory bowel disease | 298,717 (no control group) | Infliximab, adalimumab | Mean 7-80 months |
| Sean M. McConachie et al., 2018 | No | Systematic review of meta-analyses and cohort studies | Inflammatory bowel disease | Not mentioned | Infliximab, adalimumab, certolizumab, golimumab | Not mentioned |
| R. Pereira et al., 2017 | No | Observational cohort study | Immune-mediated inflammatory diseases | Not mentioned | Not specified | January 2000-December 2014 |
| T. Bongartz et al., 2006 | No | Meta-analysis of RCTs | Rheumatoid arthritis | 3,493/1,512 | Infliximab, adalimumab | At least 12 weeks |
| X. Mariette et al., 2011 | No | Systematic review and meta-analysis of observational studies | Rheumatoid arthritis | Not mentioned | Not specified | Not mentioned |
| D. Solomon et al., 2012 | Yes | Systematic review of observational cohort studies | Rheumatoid arthritis | Not specified | Infliximab, adalimumab, etanercept | Relatively short duration |
| S. Bonovas et al., 2016 | Yes | Systematic review and meta-analysis of RCTs | Inflammatory bowel disease | 9,003/5,587 | Adalimumab, certolizumab, golimumab, infliximab, natalizumab, vedolizumab | 1-24 months, average 6.5 months |
| R. Wallis et al., 2004 | No | Registry-based study using FDA Adverse Event Reporting System | Not specified | Not mentioned | Infliximab, etanercept | January 1998-September 2002 |

## Infection Outcomes

| Study | Any infection | Serious infections | Opportunistic infections | Tuberculosis | Other notable findings |
| --- | --- | --- | --- | --- | --- |
| E. Dommasch et al., 2011 | OR 1.18 (95% CI 1.05-1.33) <br> IRR 1.01 (95% CI 0.92-1.11) | OR 0.70 (95% CI 0.40-1.21) <br> IRR 0.59 (95% CI 0.35-0.99) | Not measured | Not measured | Most common site: cellulitis |
| S. Minozzi et al., 2016 | OR 1.20 (95% CI 1.08-1.34) | OR 1.41 (95% CI 1.16-1.73) fixed effects <br> OR 1.25 (95% CI 1.01-1.55) random effects | OR 0.94 (95% CI 0.33-2.64) fixed effects <br> OR 0.81 (95% CI 0.23-2.87) random effects | OR 3.53 (95% CI 1.58-7.85) fixed effects <br> OR 3.29 (95% CI 1.48-7.33) random effects | Risk increased with longer treatment duration |
| M. Muller et al., 2020 | Not reported | Not reported | Not reported | Not reported | Focus on malignancy outcomes |
| Sean M. McConachie et al., 2018 | Meta-analyses showed inconclusive association | Not specified | Registry data suggest independent risk | Not specified | Risk factors: older age, malnutrition, diabetes, combination therapy |
| R. Pereira et al., 2017 | Not reported | IR 4.02/100 patient-years (95% CI 3.20-5.04) | Not reported | IR 0.28/100 patient-years (95% CI 0.12-0.66) <br> 60% extrapulmonary | Most frequent site: gastrointestinal system <br> TB exclusively with monoclonal antibodies |
| T. Bongartz et al., 2006 | Not reported | OR 2.0 (95% CI 1.3-3.1) <br> NNH 59 (95% CI 39-125) for 3-12 months | Not reported | Not reported | Not specified |
| X. Mariette et al., 2011 | Not reported | Not reported | Not reported | Not reported | Study focused on malignancy outcomes |
| D. Solomon et al., 2012 | Not reported | Not reported | Not reported | Not reported | Study focused on malignancy outcomes |
| S. Bonovas et al., 2016 | OR 1.19 (95% CI 1.10-1.29) <br> NNH 26 | OR 0.89 (95% CI 0.71-1.12) <br> OR 0.56 (95% CI 0.35-0.90) in low-risk bias studies | OR 1.90 (95% CI 1.21-3.01) <br> NNH 194 | OR 2.04 (95% CI 0.71-5.89) | Specific pathogens: M. tuberculosis, JC virus, Nocardia, CMV/EBV, candidiasis, VZV, P. jirovecii, H. capsulatum |
| R. Wallis et al., 2004 | Not reported | Not reported | 239/100,000 for infliximab vs 74/100,000 for etanercept | 144/100,000 for infliximab vs 35/100,000 for etanercept | 3.25-fold greater risk with infliximab vs etanercept <br> 72% of infections within 90 days for infliximab |

## Malignancy Outcomes

| Study | All-site malignancy | Non-melanoma skin cancer | Melanoma | Lymphoma | Other solid tumors |
| --- | --- | --- | --- | --- | --- |
| E. Dommasch et al., 2011 | OR 1.48 (95% CI 0.71-3.09) <br> IRR 0.99 (95% CI 0.51-1.90) | OR 1.33 (95% CI 0.58-3.04) <br> 70.6% of all malignancies | Not separately analyzed | OR 1.26 (95% CI 0.39-4.15) when NMSC excluded | Prostate and breast cancer reported |
| M. Muller et al., 2020 | 1.0% overall occurrence <br> No significant association in 10/11 studies | 123/692 cases (17.8%) | Not specified | 106/692 cases (15.3%) <br> One study found increased risk | Digestive malignancies: 120/692 (17.3%) |
| R. Pereira et al., 2017 | IR 1.75/100 patient-years (95% CI 1.24-2.47) | Not specified | Not specified | Not specified | Not specified |
| T. Bongartz et al., 2006 | OR 3.3 (95% CI 1.2-9.1) <br> NNH 154 (95% CI 91-500) for 6-12 months | Not separately analyzed | Not separately analyzed | Not separately analyzed | Dose-dependent relationship observed |
| X. Mariette et al., 2011 | OR 0.95 (95% CI 0.85-1.05) | OR 1.45 (95% CI 1.15-1.76) | OR 1.79 (95% CI 0.92-2.67) | OR 1.11 (95% CI 0.70-1.51) | No evidence longer exposure increases risk |
| D. Solomon et al., 2012 | Various estimates from different studies | OR 1.24 (95% CI 0.97-1.58) alone <br> RR 1.97 (95% CI 1.51-2.58) with MTX | Not specified | Risk estimates ranged 1.1-4.9 <br> SIR 1.8-6.0 among TNFi users | Hematologic malignancies SIR 2.0-4.1 |
| S. Bonovas et al., 2016 | OR 0.90 (95% CI 0.54-1.50) <br> 0.45% treatment vs 0.54% placebo | Not separately analyzed | Not separately analyzed | Not separately analyzed | Insufficient data on exposure/follow-up |

## Mechanistic Insights

TNF plays a critical role in immune surveillance and host defense, creating a theoretical framework for both infection and malignancy risks with TNF inhibition. Multiple biological pathways have been proposed to explain the observed safety signals.

For infections, TNF-α antagonists suppress inflammatory pathways that are essential for immune defense. The disruption of granuloma formation represents a key mechanism for tuberculosis reactivation, as granulomas are crucial for containing mycobacterial infections. This mechanistic understanding explains why tuberculosis risk is elevated 3- to 4-fold and why TB occurs exclusively with monoclonal antibodies that more completely neutralize TNF, compared to the soluble receptor etanercept which may have different immunologic effects.

For malignancies, competing mechanisms have been proposed. TNF may suppress tumor development through induction of apoptosis and suppressive effects on gene expression, suggesting that TNF-blockade could enhance cancer risk. Additionally, TNF serves as a key element of inflammatory responses whose inhibition may increase risk of infection-driven cancers, particularly viral malignancies.

## Risk Factors and Population Heterogeneity

Several patient and treatment characteristics modified infection and malignancy risk. Older age emerged as a risk factor for infections, though one meta-regression found no significant age association. Comorbid conditions including malnutrition and diabetes increased infection susceptibility. Concomitant immunosuppressive therapy represented an important modifier, with evidence of synergistic effects when combining TNF-blockers with other systemic immunosuppressants. Disease-specific factors showed variable effects. For infections, Crohn’s disease patients demonstrated higher opportunistic infection risk compared to ulcerative colitis.

## Synthesis

The systematic review data reveal a complex safety profile for TNF-blockers that cannot be reduced to simple risk estimates. The apparent contradictions in findings—particularly for serious infections and malignancies—can be reconciled by considering methodological factors, population characteristics, and temporal dynamics.

## References

1. Sean M. McConachie, S. Wilhelm, A. Bhargava, P. Kale-Pradhan. (2018). Biologic-Induced Infections in Inflammatory Bowel Disease: The TNF-α Antagonists. The Annals of Pharmacotherapy.
2. R. Pereira, Raquel Faria, P. Lago, T. Torres. (2017). Infection and Malignancy Risk in Patients Treated with TNF Inhibitors for Immune-Mediated Inflammatory Diseases. Current Drug Safety.
3. T. Bongartz, A. Sutton, M. Sweeting, I. Buchan, E. Matteson, and 1 more. (2006). Anti-TNF antibody therapy in rheumatoid arthritis and the risk of serious infections and malignancies: systematic review and meta-analysis of rare harmful effects in randomized controlled trials. Journal of the American Medical Association (JAMA).
4. X. Mariette, M. Matucci-Cerinic, K. Pavelka, P. Taylor, R. V. van Vollenhoven, and 5 more. (2011). Malignancies associated with tumour necrosis factor inhibitors in registries and prospective observational studies: a systematic review and meta-analysis. Annals of the Rheumatic Diseases.
5. E. Dommasch, K. Abuabara, D. Shin, Josephine C. Nguyen, A. Troxel, and 1 more. (2011). The risk of infection and malignancy with tumor necrosis factor antagonists in adults with psoriatic disease: a systematic review and meta-analysis of randomized controlled trials. Journal of American Academy of Dermatology.
6. D. Solomon, E. Mercer, A. Kavanaugh. (2012). Observational studies on the risk of cancer associated with tumor necrosis factor inhibitors in rheumatoid arthritis: a review of their methodologies and results. Arthritis & Rheumatism.
7. S. Minozzi, S. Bonovas, T. Lytras, V. Pecoraro, Marien González-Lorenzo, and 12 more. (2016). Risk of infections using anti-TNF agents in rheumatoid arthritis, psoriatic arthritis, and ankylosing spondylitis: a systematic review and meta-analysis. Expert Opinion on Drug Safety.
8. S. Bonovas, G. Fiorino, M. Allocca, T. Lytras, G. Nikolopoulos, and 2 more. (2016). Biologic Therapies and Risk of Infection and Malignancy in Patients With Inflammatory Bowel Disease: A Systematic Review and Network Meta-analysis. Clinical Gastroenterology and Hepatology.
9. R. Wallis, M. Broder, J. Y. Wong, M. Hanson, D. Beenhouwer. (2004). Granulomatous infectious diseases associated with tumor necrosis factor antagonists. Clinical Infectious Diseases.
10. M. Muller, F. D'amico, S. Bonovas, S. Danese, L. Peyrin-Biroulet. (2020). TNF inhibitors and risk of malignancy in patients with inflammatory bowel diseases: a systematic review. Journal of Crohn's & Colitis.